1. Field of the Invention
The present invention relates to an ultrasonic diagnostic device and in particular to a three-dimensional ultrasonic diagnostic device for measuring and diagnosing movement of a target tissue.
2. Description of the Related Art
Ultrasonic diagnosis devices are used for diagnosing abnormal movement of a target tissue, for example, abnormal expansion and retraction movements of a heart. In order to diagnose abnormal movement of a target tissue, it is desirable to use an ultrasonic diagnostic device which can precisely capture the movement of the target tissue. To achieve this object, in conventional ultrasonic diagnostic devices, a two-dimensional ultrasonic image in which the outline of the target tissue is clarified is obtained for each frame, a displacement image corresponding to a difference between an image of an earlier frame and an image of the most recent frame is time sequentially synthesized to form a displacement history image, and the displacement history image is displayed (refer to, for example, Japanese Patent No. 3045642). With a two-dimensional ultrasonic diagnostic device having such functionality, it is possible to detect abnormal movements of target issue and positions where an abnormality occurred in the target tissue with a high degree of sensitivity.
With the development of ultrasonic technologies, it has become possible to employ for diagnosis three-dimensional ultrasonic diagnostic devices which can three-dimensionally express a target tissue within a three-dimensional space. The advantages of such three-dimensional ultrasonic diagnostic devices are particularly significant in the ultrasonic observation and diagnosis of an organ such as the heart. For example, by observing the expansion and retraction movements of the heart using a three-dimensional diagnostic device, it is possible for a user to comprehend the three-dimensional shape of the heart, which is much more difficult with two-dimensional ultrasonic diagnostic devices. The advantages of the comprehension of the three-dimensional shape are also true in a displacement history image in the conventional ultrasonic diagnostic device as described above. That is, by realizing a display method in a three-dimensional ultrasonic diagnostic device which allows visual comprehension of the displacement of the target tissue, it is possible to more precisely diagnose abnormal movements of a heart.